Cooperative Extension Service, University of 

 Illinois College of Agriculture in Cooperation With 

 the Illinois Natural History Survey and U.S.D.A. 



FOR IMMEDIATE RELEASE April 29, 1966 



INSECT SURVEY BULLETIN NO. 2 



This second weekly bulletin of 1966 on the general insect situation in 

 Illinois (fruit insects excepted), prepared by entomologists of the University of 

 Illinois College of Agriculture, Illinois Natural History Survey and cooperating 

 agencies, reports general trends in insect activity and suggests abbreviated con- 

 trol measures. Each individual should check his own fields to determine local 

 conditions. 



The alfalfa weevil is seriously damaging alfalfa fields in an area south 

 of Highway 13. Infestation and damage vary considerably from field to field, but 

 it is obvious that treatment is already too late for some fields. In many fields 

 the terminal leaves are completely destroyed, and the larvae are now feeding on 

 the lower leaves. Overwintering adults are still laying eggs and will continue 

 to do so for several weeks. Some larvae are just beginning to pupate (feeding 

 stops in this resting stage) but, with continued egg laying, populations of larvae 

 can be expected to remain high for the next two or three weeks. 



In the area between Highways 13 and 50, the infestations are lower, but 

 some fields are showing as high as 50$ terminal feeding. 



Fields showing 75^ or more terminal feeding and live larvae should be 

 treated immediately. Serious damage can occur within a few days after the 75% 

 feeding level is reached, so treatment must be made promptly. Some fields may 

 need to be retreated in two or three weeks if problems recur. However, by that 

 time it may be wiser to cut the alfalfa, remove the hay and then treat the new 

 growth. 



Parathion or azinphosmethyl (Guthion) at 1/2 pound per acre is effective, 

 but because both are toxic they should be applied only by experienced applicators. 

 Azinphosmethyl should not be applied within 21 days of harvest or more than once 

 per cutting, and parathion should not be applied within 15 days of cutting. 



If you wish to make your own applications and temperatures are prefer- 

 ably above 60° , use 1 pound of malathion per acre or a commercially prepared 

 diazinon-methoxychlor mixture. Use a minimum of 10 gallons of water per acre 

 when spraying. There is no waiting period between application of malathion and 

 harvest. Allow one week to elapse between application of diazinon-methoxychlor 

 and harvest. 



For pastures, use malathion or the diazinon-methoxychlor mixture. You 

 can put animals right back on pastures sprayed with malathion, but wait one week 

 when using diazinon-methoxychlor sprays. 



Clover leaf weevil are large, tightly curled green worms with white 

 stripes down the back that hide at the base of both clover and alfalfa plants 

 during the day. They can be easily confused with alfalfa weevil larvae. The 

 clover leaf weevil larva has a tan to brown head, while the alfalfa weevil larva 

 has a black head. Parasites and a fungus disease have in the past killed many 

 clover leaf weevils, preventing serious buildups. The rapid growth of alfalfa 

 and red clover is encouraging, as it enables plants to recover rapidly. No seri- 

 ous damage by this insect has yet been observed. 



